5. The term “previously dried” without qualification signifies that the substance shall be dried as directed under Loss on Drying <731> or Water Determination <921> (gravimetric determination).
6. Where drying in vacuum over a desiccant is directed, a vacuum desiccator, a vacuum drying pistol, or other suitable vacuum drying apparatus shall be used.
6. Where drying in vacuum over a desiccant is directed, a vacuum desiccator, a vacuum drying pistol, or other suitable vacuum drying apparatus shall be used.